3D Chip Interconnection Pads for Misalignment Tolerance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing 3D integrated circuits face challenges in maintaining consistent electrical performance due to misalignment between stacked chips, which affects bonding quality and reliability, and current solutions complicate manufacturing with uneven metal distribution and planarization difficulties.
Innovation Solution
A 3D stack design featuring interconnection pads with specific pitch and dimension relationships between chips, ensuring a constant contact surface and improved metal density, allowing for tolerance to misalignment and simplified manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional 3D stacking with standard interconnection pad arrangements is used, then manufacturing is simpler, but misalignment between chips degrades bonding quality and electrical performance
Solution Approach 1:
The patent applies asymmetry by designing interconnection pads with different dimensions in the two principal directions (length along x-axis vs width along y-axis). Specifically, the pads have a length that is a multiple of the pitch in one direction and a width that is a multiple of the pitch in the perpendicular direction, creating an asymmetric rectangular pattern that provides tolerance to misalignment while maintaining reliable electrical contact
Solution Approach 2:
The patent implements local quality by varying the dimensions of interconnection pads at different locations on the chip. The pads are designed with specific length and width ratios that are multiples of the pitch, creating locally optimized contact areas that ensure consistent bonding quality even when global misalignment occurs during stacking
2Reliability
If interconnection pads are designed to tolerate misalignment, then bonding reliability improves, but metal distribution becomes uneven and planarization becomes difficult
Solution Approach 1:
The patent applies parameter changes by systematically varying the dimensions of interconnection pads based on their position relative to the pitch grid. By defining pad length and width as specific multiples of the pitch (e.g., 2x pitch, 3x pitch), the design achieves homogeneous metal distribution across the chip surface, which facilitates planarization while maintaining misalignment tolerance
Solution Approach 2:
The patent implements homogeneity by creating a regular, periodic pattern of interconnection pads where each pad's dimensions are defined as multiples of the pitch. This systematic arrangement ensures uniform metal distribution across the bonding surface, making the surface easier to planarize while maintaining consistent bonding reliability throughout the chip
3Reliability
If misalignment tolerance is increased, then bonding robustness improves, but electrical performance consistency deteriorates
Solution Approach 1:
The patent resolves this contradiction by using asymmetric rectangular pad geometry where the length and width are different multiples of the pitch. This asymmetry allows the pad to maintain adequate contact area even with misalignment, while the specific dimensional ratios ensure that electrical performance remains consistent across varying alignment conditions
Solution Approach 2:
The patent applies preliminary action by pre-designing the interconnection pad dimensions as specific multiples of the pitch before the bonding process. This preliminary geometric configuration ensures that regardless of misalignment occurring during bonding, the electrical contact area remains sufficient and consistent, thereby maintaining electrical performance consistency while providing bonding robustness
Data Source
AI summary
A 3D stack includes a first chip having first interconnection pads of rectangular section, the first interconnection pads having a first pitch in a first direction and a second pitch in a second direction perpendicular to the first direction; and a second chip having second interconnection pads, the second interconnection pads having a third pitch in the first direction and a fourth pitch in the second direction, at least one part of the second interconnection pads being in contact with the first interconnection pads to electrically couple the first and second chips. The first interconnection pads have a first dimension in the first direction equal to m times the third pitch and a second dimension in the second direction equal to n times the fourth pitch. The first interconnection pads are separated two by two in the first direction by a first distance equal to q times the third pitch.